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Difficulty: MediumNewton's First Law (Inertia)

A passenger train is traveling forward at a constant velocity on a straight, level track. If a passenger places a smooth cup of coffee on a perfectly level table inside the train, the cup will continuously slide backward relative to the table due to the train's high forward speed.

Answer: Answer

Answer

False
Because the train is traveling at a constant velocity, the cup maintains its state of uniform motion along with the train. Due to inertia, it requires an unbalanced force (such as the train accelerating or braking) to change its speed relative to the table. Therefore, it will not slide backward simply because the train is moving fast.

Step-by-Step Solution

1
Analyze the motion of the train system.
The train is moving at a constant velocity on a straight, level track, meaning its acceleration is zero.
Identifying the state of motion (acceleration vs. constant velocity) is necessary to apply Newton's Laws correctly.
2
Determine the state of motion of the cup.
The cup is inside the train, so it already shares the train's constant forward velocity.
Objects within a moving reference frame share the velocity of that frame.
3
Apply Newton's First Law of Motion (Inertia).
Since there is zero acceleration, there is no unbalanced net force acting horizontally on the cup. The cup will remain at rest relative to the table.
Newton's First Law dictates that without an unbalanced external force, an object's velocity remains constant.

Key Concept

Newton's First Law (Inertia) and Constant Velocity
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Topics

Newton's First Law (Inertia)

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